The ornamental design for a telephonehandset, as shown and described.
FIG. 1 is a top front perspective view of a telephone handset of the present invention;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a first side view thereof;
FIG. 5 is a second side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line showing of the remainder of the telephone handset is directed to environment and is for illustrative purposes only; the broken lines forms no part of the claimed design.